1. Field of Invention
The present invention relates to semiconductor fabrication, and more particularly relates to microelectromechanical system (MEMS) device and fabrication method thereof.
2. Description of Related Art
The MEMS device, such as the MEMS microphone, basically includes a backplate and a diaphragm over a silicon substrate. The backplate has venting holes, the silicon substrate has a cavity, so that the cavity is connected to a chamber, which is formed between the backplate and the diaphragm, through the venting holes. The diaphragm can sense the air pressure caused by sound wave, resulting in change of capacitance between the diaphragm and the back plate, accordingly. The detecting voltage signal includes the capacitance effect, thus the sound can be sensed. The performance of MEMS microphone then can be achieved.
However, MEMS device can be formed in various structures, which also cause different performances. How to design a proper MEMS device is still an issue for further development.